Unable to send a message with createRoomStory GraphQL

Question

I am trying to integrate the send message API to a room. But unable to get a better help from the documentation. Unable to fund the related values to be put in the object.

Can someone please share some working example?

https://www.upwork.com/developer/documentation/graphql/api/docs/index.html#mutation-createRoom

{
"input":
{
    "roomId": "room_44ff94604cd3e77bd8fd16f654eb5a7d",
    "suppressNotification": true,
    "actionType": "hr:enable",
    "actionTense": "enabled",
    "message": "xyz789",
    "sourceClient": "1316130623044288513",
    "newObjectReferences":
    {
        "objectType": "abc123",
        "externalId": "4",
        "appId": "xyz789",
        "objectForm": "1316130623044288513"
    },
    "actionRequired": false,
    "integrationData": null,
    "metadata": [],
    "publishedFromMC": true,
    "renderTemplate": "xyz789",
    "messageId": 4
}}

Getting error

{
  "errors": [
    {
      "message": "'roomsDS',  'AddStoryToRoomHysCmd',  'Object type not found for name: abc123'",
      "locations": [
        {
          "line": 2,
          "column": 3
        }
      ],
      "path": [
        "createRoomStory"
      ],
      "extensions": {
        "code": "OBJECT_TYPE_NOT_FOUND",
        "details": ""
      }
    }
  ],
  "data": null
}